3drenderings/iStock/Thinkstock(TAMPA, Fla.) -- The father of the suspected Tampa serial killer is refusing to speak to investigators, court documents show.

A judge is scheduled to rule on whether Howell Donaldson, Jr. should be held in contempt for refusing to provide testimony to state prosecutors Tuesday, despite a subpoena that ordered him to do so, according to a motion filed Wednesday.

On Monday, Howell Donaldson, Jr. was served with the subpoena directing him to appear at the Office of the State Attorney to provide "truthful testimony" on Tuesday at 2 p.m. When he and his lawyer Ralph Fernandez arrived, he "refused to answer any question related to the investigation."

His son, Howell Donaldson III, is charged with four counts of first-degree murder for the shooting deaths of four people in Tampa's Seminole Heights neighborhood between Oct. 9 and Nov. 14.

At the Office of the State Attorney, Howell Donaldson, Jr. was placed under oath. A court reporter explained to him that he did not have a constitutional right against self-incrimination and did not have the right to refuse to answer questions from the assistant state attorney, as a result of the immunity granted to him by Florida law, the motion states.

He would not answer any questions related to his son's background, developmental history, mode of transportation, gun possession and ownership or state of mind, according to the court document.

"Mr. Donaldson’s refusal to testify in the above-described proceeding, despite having received a court-authorized subpoena, constitutes indirect criminal contempt of this Honorable Court," the motion states.

The motion orders Howell Donaldson Jr. to appear in court and answer why he should not be held in indirect criminal contempt of court for "willfully refusing to comply with a lawful, court-authorized subpoena."

Rosita Donaldson, the murder suspect's mother, is "likewise implicated in the process," despite not being named in the motion, Fernandez told ABC News. She and her husband will appear in court for the contempt hearing Thursday morning, where their attorneys will provide "different kinds of evidence for why they should not be sanctioned," Fernandez said.

Florida state law does not allow for parent-child privilege, which the Donaldsons' attorneys will address during the hearing, Fernandez said.

"I think it shocks the conscience of Americans to be part of a system of justice that is identical on this issue as North Korea, Cuba, Syria and Iran, where parents are compelled to testify against their children and children against their parents," he said.

The Donaldsons were "fully advised" on their actions and are "ready to take the consequence," Fernandez said, describing the situation as "tough" and "complex."

Tampa police arrested Howell Donaldson III on Nov. 28 after his manager at an Ybor City McDonald's alerted police to a McDonald's bag containing a firearm, which authorities later matched to the weapon used to kill all four victims.

On Friday, Howell Donaldson Jr. and his wife, Rosita Donaldson, held a press conference stating that they were "devastated" at the news of their son's arrest and were praying for the families of the victims.

"I prayed for those families when it first started," Rosita Donaldson said at the press conference, holding back tears. "And then when they arrested my son, devastation, because I love my son and it was disbelief that this was happening to our family. And we question why."

At the press conference, Fernandez told reporters that his clients would not talk about "any of the facts related to the prosecution or the defense of the case."

Howell Donaldson III is currently being held in a Hillsborough County jail without bond. A pre-trial detention hearing scheduled for Tuesday was canceled because the case has not yet been assigned to a division. He has not yet entered a plea.

Fernandez did not immediately respond to ABC News' request for comment.